/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.extensions.euphoria.core.client.operator;



import com.bff.gaia.unified.sdk.annotations.Internal;

import com.bff.gaia.unified.sdk.extensions.euphoria.core.client.operator.base.Operator;

import com.bff.gaia.unified.sdk.extensions.euphoria.core.translate.OperatorTransform;

import com.bff.gaia.unified.sdk.values.KV;

import com.bff.gaia.unified.sdk.values.PCollection;

import com.bff.gaia.unified.sdk.values.PCollectionList;

import com.bff.gaia.unified.sdk.values.TypeDescriptor;



import javax.annotation.Nullable;



/**

 * Internal operator used to extract values from keyed output.

 *

 * @param <InputT> input type

 * @param <KeyT> key type

 * @param <OutputT> output type

 */

@Internal

class OutputValues<InputT, KeyT, OutputT> extends Operator<OutputT>

    implements CompositeOperator<InputT, OutputT> {



  private final Operator<KV<KeyT, OutputT>> keyedOperator;



  OutputValues(

      @Nullable String name,

      @Nullable TypeDescriptor<OutputT> outputType,

      Operator<KV<KeyT, OutputT>> keyedOperator) {

    super(name, outputType);

    this.keyedOperator = keyedOperator;

  }



  @Override

  public PCollection<OutputT> expand(PCollectionList<InputT> inputs) {

    final PCollection<KV<KeyT, OutputT>> keyedOutput =

        OperatorTransform.apply(keyedOperator, inputs);

    return MapElements.named("ExtractValues")

        .of(keyedOutput)

        .using(KV::getValue, getOutputType().orElse(null))

        .output();

  }

}